OBJECTIVES: The objective was to investigate the patient-reported diabetes symptoms predictors of generic health-related quality of life (HRQOL) in adolescents and young adults (AYA) with type 1 or type 2 diabetes. METHODS: The 15-item PedsQL 3.2 Diabetes Module Diabetes Symptoms Summary Score and PedsQL 4.0 Generic Core Scales were completed in a 10-site national field test study by 513 AYA ages 13-25 years with type 1 (n = 424) or type 2 (n = 89) diabetes. Diabetes symptoms were tested for bivariate and multivariate linear associations with generic HRQOL. RESULTS: Diabetes symptoms were associated with decreased HRQOL in bivariate analyses. In predictive analytics models utilizing hierarchical multiple regression analyses controlling for relevant demographic and clinical covariates, diabetes symptoms accounted for 38 and 39% of the variance in patient-reported generic HRQOL for type 1 and type 2 diabetes, respectively, reflecting large effect sizes. The diabetes symptoms facets hyperglycemia symptoms, hypoglycemia symptoms, and nonspecific diabetes symptoms individually accounted for a significant percentage of the variance in separate exploratory predictive analytics models after controlling for demographic and clinical covariates, with small-to-large effect sizes. CONCLUSIONS: Diabetes symptoms are potentially modifiable predictors of generic HRQOL in AYA with diabetes. Identifying specific diabetes symptoms or symptoms facets that are the most important predictors from the patient perspective facilitates a patient-centered approach in clinical research, clinical trials, and practice designed to enhance overall generic HRQOL in AYA with diabetes.